Growth rates of organisms are routinely used to summarize physiological performance, but the consequences of local evolutionary history and ecology are largely missed by analyses on wide biogeographical scales. This broad approach has been commonly applied to other physiological parameters across terrestrial and aquatic environments. Here, we examine growth rates of marine bivalves across all biogeographical realms, latitude, and temperature, with analyses to determine regional effects on growth on global scales.
Global: marine ecosystems.
1930–2018.
Bivalves.
We use a comprehensive data set of bivalve growth parameters (n = 966, 243 species) representing all biogeographical realms to calculate overall growth performances. We use these data with environmental temperature to analyse global patterns in growth, accounting for regional primary productivity and phylogeny using general additive mixed and linear models. The Arrhenius relationship and corresponding activation energies are used to quantify the sensitivity to temperature in each biogeographical realm and province.
Our analyses show that bivalve growth demonstrates latitudinal asymmetry and exhibits nonlinear relationships with latitude. We find that overall growth performance is affected by temperature and particulate organic carbon, but the form of these relationships differs with phylogeny. Growth is slower and more sensitive to increasing temperature in the Antarctic than it is in the Arctic, and decreases with increasing temperature in some tropical realms, a previously unidentified and fundamental difference in growth and physiological sensitivity.
Our findings provide compelling evidence that the widely used curvilinear relationship between temperature and growth rates in marine ectotherms is an inappropriate descriptor of thermal sensitivity, because it normalizes regional variations in physiological performance. Without a more detailed assessment of global physiological patterns, the responses of species to local variations associated with climate change will be under-appreciated in global assessments of climate risk, minimizing the effectiveness of management and conservation.